No abstract

Mercury is a xenobiotic metal that is a highly deleterious environmental pollutant. The biotransformation of mercury chloride (HgCl 2 ) into methylmercury chloride (CH 3 HgCl) in aquatic environments is well-known and humans are exposed by consumption of contaminated fish, shellfish and algae. The objective of the present study was to determine the changes induced in vitro by two mercury compounds (HgCl 2 and CH 3 HgCl) in cultured human lymphocytes. Short-term human leukocyte cultures from 10 healthy donors (5 females and 5 males) were set-up by adding drops of whole blood in complete medium. Cultures were separately and simultaneously treated with low doses (0.1 to 1000 µg/l) of HgCl 2 and CH 3 HgCl and incubated at 37ºC for 48 h. Genotoxicity was assessed by chromosome aberrations and polyploid cells. Mitotic index was used as a measure of cytotoxicity. A significant increase (P < 0.05) in the relative frequency of chromosome aberrations was observed for all concentrations of CH 3 HgCl when compared to control, whether alone or in an evident sinergistic combination with HgCl 2 . The frequency of polyploid cells was also significantly increased (P < 0.05) when compared to control after exposure to all concentrations of CH 3 HgCl alone or in combination with HgCl 2 . CH 3 HgCl significantly decreased (P < 0.05) the mitotic index at 100 and 1000 µg/l alone, and at 1, 10, 100, and 1000 µg/l when combined with HgCl 2 , showing a synergistic cytotoxic effect. Our data showed that low concentrations of CH 3 HgCl might be cytotoxic/genotoxic. Such effects may indicate early cellular changes with possible biological consequences and should be considered in the preliminary evaluation of the risks of populations exposed in vivo to low doses of mercury.